JP2011135488A - Wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system in which calibration data are converted in a proper communication mode and calibration data for a data amount required for measurement can be transmitted. <P>SOLUTION: A quality detection section 151 compares and determines a CIR with a CIR threshold, an error rate with an error rate threshold, and a data amount with a data amount threshold to detect whether or not a quality measurement based on calibration data is properly performed. A measurement priority control section 152 determines the priority orders and data amounts of terminals 200 to perform the quality measurement on the basis of the detection result of the quality measurement. A scheduler 143a extracts calibration data from a buffer 142 and determines a transmission destination and the rate of the calibration data on the basis of the priority order and the data amount. An MCS (modulation and coding scheme) selection section 144a selects the modulation scheme and the coding rate of an MCS of a rate designated by an MCS selection table 132a and outputs to a modulation section 145 the calibration data, the modulation system and the coding rate of the MCR. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication system, and in particular, transmits communication quality measurement data (hereinafter referred to as calibration data) to a terminal to measure the communication quality, and a base station transmits to the terminal according to the measured communication quality. The present invention relates to a radio communication system that selects a communication mode (Modulation and Coding Scheme, hereinafter referred to as MCS) that is a modulation scheme and coding rate of data to be transmitted.

  In a wireless communication system, various system controls are performed in order to perform data communication with high quality and high efficiency. For example, control of transmission / reception power, change of modulation scheme / encoding scheme, control of communication channel, switching of cells, and the like are performed, thereby contributing to improvement of communication quality and power saving of the system. In recent years, carrier-to-interference ratio (hereinafter referred to as CIR) of communication data, error rate (hereinafter referred to as error rate) such as PER (packet error rate) and BER (bit error rate) are measured, There is a function for improving the communication quality of data by selecting the MCS based on the measured communication quality. A conventional technique for improving such communication quality will be described with reference to the drawings.

  A configuration of a wireless communication system 10 according to the prior art is shown in FIG. The radio communication system 10 includes a base station 100 and a plurality of terminals 200 that communicate with the base station 100. FIG. 6 shows the configuration of the base station 100 in the wireless communication system 10 according to the prior art. As illustrated in FIG. 6, the base station 100 includes an antenna duplexer 110, a receiving unit 120, a table updating unit 130, and a transmitting unit 140. An antenna 111 is connected to the antenna duplexer 110. The reception unit 120 includes a reception RF unit 121, a demodulation unit 122, a CIR decoding unit 123, and an error rate decoding unit 124. Further, the demodulation unit 122, the CIR decoding unit 123, and the error rate decoding unit 124 are provided for each terminal 200 that communicates with the base station 100. The table updating unit 130 includes a table rewriting unit 131, an MCS selection table 132, and a terminal information table 133. The MCS selection table 132 is provided for each terminal 200 that communicates with the base station 100. The transmission unit 140 includes a buffer 141, a buffer 142, a scheduler 143, an MCS selection unit 144, a modulation unit 145, and a transmission RF unit 146.

  First, the MCS selection table 132 will be described. The configuration of the MCS selection table 132 is shown in FIG. The MCS selection table 132 includes items of Intex No (I), MCS modulation method, coding rate, CIR, and error rate. A unique number for identifying calibration data is set in the Intex No (I). In the MCS modulation scheme and coding rate, the MCS modulation scheme and coding rate of the calibration data transmitted from the base station 100 to the terminal 200 are set. For example, there are modulation schemes such as BPSK, QPSK, 16QAM, and 64QAM, and any of these schemes is set. The coding rate includes coding rates such as 1/2, 3/4, and the coding rate corresponding to the modulation scheme is set. In the CIR, the CIR for the calibration data transmitted from the terminal 200 that has received the calibration data to the base station 100 is set. As the error rate, an error rate for the calibration data transmitted from the terminal 200 that has received the calibration data to the base station 100 is set.

  Next, the terminal information table 133 will be described. The configuration of the terminal information table 133 is shown in FIG. The terminal information table 133 includes items of terminal name, MCS modulation scheme and coding rate, and error rate threshold. As the terminal name, a unique name assigned to each terminal 200 is set. In the MCS modulation scheme and coding rate, the MCS modulation scheme and coding rate selected when the base station 100 transmits data other than calibration data (hereinafter referred to as transmission data) are set. The modulation scheme and coding rate are the same as the modulation scheme and coding rate in the MCS selection table 132. In the error rate threshold, an allowable range (such as an upper limit value) of an error rate of transmission data between the base station 100 and the terminal 200 is set.

  Next, processing of each function constituting the base station 100 will be described with reference to FIG.

  The antenna duplexer 110 connects the receiving unit 120 and the transmitting unit 140 to the antenna 111, switches to the receiving unit 120 side when inputting a signal from the antenna 111, and switches to the transmitting unit 140 side when outputting a signal to the antenna 111. Switch.

  Next, each function of the receiving unit 120 will be described. The reception RF unit 121 performs predetermined down-conversion on the reception signal input from the antenna duplexer 110, further converts the down-converted reception signal from an analog signal to a digital signal, and outputs the converted signal to the demodulation unit 122. The demodulation unit 122 demodulates the reception signal input from the reception RF unit 121. The CIR decoding unit 123 decodes the CIR information of the calibration data input from the demodulation unit 122, and outputs it to the table rewriting unit 131, the scheduler 143, and the MCS selection unit 144. The error rate decoding unit 124 decodes the error rate information of the calibration data input from the demodulation unit 122 and outputs it to the table rewriting unit 131.

  Next, each function of the table update unit 130 will be described. The table rewriting unit 131 receives the CIR of the I-th calibration data (hereinafter referred to as calibration data (I)) from the CIR decoding unit 123, and the error rate of the calibration data (I) from the error rate decoding unit 124. When the MCS modulation method and coding rate of calibration data (I) are input from the MCS selection unit 144, the input CIR, error rate, MCS modulation method and coding rate are set in the MCS selection table 132. . For example, the table rewriting unit 131 inputs the CIR “c2” of the calibration data (2) from the CIR decoding unit 123, the error rate “e2” of the calibration data (2) from the error rate decoding unit 124, and the MCS. When the modulation method “q2” and the coding rate “r2” of the calibration data (2) are input from the selection unit 144, the MCS modulation method corresponding to the index No (I) “2” is obtained as shown in FIG. “Q2”, “r2” as the coding rate, “c2” as the CIR, and “e2” as the error rate are set.

  Next, each function of the transmission unit 140 will be described. The buffer 141 is an area for temporarily storing transmission data. The buffer 142 is an area for temporarily storing calibration data. If the transmission data is stored in the buffer 141, the scheduler 143 extracts the transmission data from the buffer 141, and extracts the CIR from the CIR decoding unit 123 corresponding to the destination terminal 200. Next, the scheduler 143 performs transmission data scheduling based on the CIR, specifies a transmission destination, and outputs the transmission destination to the MCS selection unit 144. If the transmission data is not stored in the buffer 141, the scheduler 143 takes out the calibration data from the buffer 142, schedules the calibration data, designates the transmission destination, and outputs it to the MCS selection unit 144.

  When the MCS selection unit 144 transmits transmission data, the CIR is extracted from the CIR decoding unit 123 corresponding to the transmission destination terminal 200, and the transmission data error rate threshold corresponding to the transmission destination terminal 200 is extracted from the terminal information table 133. Take out. Then, based on this CIR, the MCR modulation method and coding rate that fall within the error rate threshold range are selected from the MCS selection table 132, and the selected MCR modulation method and coding rate are set in the MCR of the terminal information table 133. Set to modulation method and coding rate. Then, the MCS selection unit 144 outputs the transmission destination, transmission data, MCR modulation scheme and coding rate to the modulation unit 145. For example, the transmission destination is “terminal A”, the CIR input from the CIR decoding unit 123 corresponding to “terminal A” by the MCS selection unit 144 is “ca”, and the terminal name “terminal A” in the terminal information table 133 corresponds. If the transmission data error rate threshold is “ea”, the MCS modulation scheme “q2” and coding rate “r2” within the range of the error rate threshold “ea” based on the value of “ca” are selected by the MCS. Selected from table 132. By this selection, “q2” is set as the MCS modulation scheme corresponding to the terminal name “terminal A” in the terminal information table 133, and “r2” is set as the MCS coding rate. When the MCS selection unit 144 transmits calibration data, the MCS is selected in a predetermined order, and the transmission destination, calibration data, MCR modulation method and coding rate are sent to the modulation unit 145. Output.

  When the modulation unit 145 transmits transmission data, the transmission destination, the transmission data, and the modulation method and coding rate of the MCR are input from the MCS selection unit 144, and the transmission data is modulated by the modulation method and coding rate. The modulated transmission data is output to the transmission RF unit 146. When the modulation unit 145 transmits calibration data, the transmission destination, the calibration data, and the MCR modulation method and coding rate are input from the MCS selection unit 144, and the calibration data is modulated by the modulation method and coding rate. The transmission destination and the modulated calibration data are output to the transmission RF unit 146. The transmission RF unit 146 converts the transmission data or calibration data input from the modulation unit 145 from a digital signal to an analog signal, further performs up-conversion, sets a transmission destination, and outputs the transmission destination to the antenna duplexer 110.

  Conventionally, the communication quality of the base station 100 and the terminal 200 is measured by selecting the MCS modulation method and coding rate in a predetermined order as described above and transmitting the calibration data. Based on the quality measurement results, the transmission data MCS modulation scheme and coding rate are selected.

  Moreover, there exists following patent document 1 as a technique which measures the communication quality of a communication system. In Patent Document 1, by controlling the base station apparatus to use one or more channel slots for data communication and another one or more channel slots for communication quality measurement communication, A technique is provided in which a terminal station apparatus can measure communication quality using a slot of a channel allocated exclusively.

JP2008-34940

  In the wireless communication system 10 according to the prior art, when transmitting calibration data, MCSs are selected in a predetermined order. At this time, since the transmission time (number of slots) of the calibration data is constant even if the MCS is different, calibration is performed with the low-rate MCS modulation scheme and coding rate for the terminal 200 whose communication quality is deteriorated. When data is modulated, the calibration data may not reach the amount of data necessary for measurement. In addition, since the transmission frequency of calibration data is not adjusted according to the communication quality, the throughput of transmission data between the base station and the terminal can be increased by transmitting the calibration data to a terminal having good communication quality. There was a decline. Also, with the technique disclosed in Patent Document 1, it is possible to efficiently measure communication quality by dividing the slots of channels for normal communication and communication quality measurement. However, there is no control for transmitting measurement data having an appropriate amount of data to perform accurate communication quality measurement, or control for transmitting measurement data at an appropriate frequency to prevent a decrease in throughput.

  This invention is made | formed in view of such a condition, and it aims at providing the radio | wireless communications system which can solve the said subject.

  The wireless communication system of the present invention transmits calibration data from a base station to a plurality of terminals communicating with the base station, and determines the communication quality between the base station and the terminal based on the error rate of the calibration data. In a wireless communication system for detecting and selecting a communication mode of transmission data to be transmitted to the terminal based on the detected communication quality, the base station includes storage means for storing a communication mode used in each of the plurality of terminals And priority setting means for preferentially using a communication mode having a low transmission rate among the communication modes stored in the storage means and transmitting the calibration data.

  According to the present invention, calibration data having a data amount necessary for measurement is transmitted to a terminal by converting calibration data with an appropriate MCS modulation method and coding rate in order to perform accurate communication quality measurement. And a wireless communication system capable of transmitting calibration data at an appropriate frequency in order to prevent a decrease in throughput of transmission data between a base station and a terminal.

It is a figure which shows the function structure of the base station which concerns on embodiment of this invention. It is a figure which shows the structure of the MCS selection table which concerns on embodiment of this invention. It is a figure which shows the structure of the terminal information table which concerns on embodiment of this invention. It is a flowchart which shows the MCS selection procedure which concerns on embodiment of this invention. It is a figure which shows the structure of the radio | wireless communications system which concerns on a prior art. It is a figure which shows the function structure of the base station which concerns on a prior art. It is a figure which shows the structure of the MCS selection table which concerns on a prior art. It is a figure which shows the structure of the terminal information table which concerns on a prior art.

  The configuration of the wireless communication system 20 in the embodiment of the present invention is the same except that the base station 100 of the wireless communication system 10 shown in FIG. FIG. 1 shows the configuration of base station 300 in radio communication system 20 according to the embodiment of the present invention. As shown in FIG. 1, the base station 300 includes an antenna duplexer 110, a receiving unit 120a, a table updating unit 130a, a transmitting unit 140a, and a terminal information monitoring unit 150. An antenna 111 is connected to the antenna duplexer 110. The reception unit 120a includes a reception RF unit 121, a demodulation unit 122, a CIR decoding unit 123a, an error rate decoding unit 124a, and a data amount decoding unit 125. Further, the demodulation unit 122, the CIR decoding unit 123a, the error rate decoding unit 124a, and the data amount decoding unit 125 are provided for each terminal 200 that communicates with the base station 300. The table updating unit 130a includes a table rewriting unit 131a, an MCS selection table 132a, and a terminal information table 133a. The MCS selection table 132a is provided for each terminal 200 that communicates with the base station 300. The transmission unit 140a includes a buffer 141, a buffer 142, a scheduler 143a, an MCS selection unit 144a, a modulation unit 145, and a transmission RF unit 146. The terminal information monitoring unit 150 includes a quality detection unit 151 and a measurement priority control unit 152. In the base station 300 according to the embodiment of the present invention, a terminal information monitoring unit 150 is added as compared with the configuration of the base station 100 of the prior art, and further, the CIR decoding unit 123a and the error rate decoding unit 124a of the receiving unit 120a The table rewriting unit 131a of the unit 130a, the MCS selection table 132a and the terminal information table 133a, the scheduler 143a of the transmission unit 140a, and the MSC selection unit 144a are different. The terminal information monitoring unit 150 includes a quality detection unit 151 and a measurement priority control unit 152. Differences from the prior art will be described with reference to the drawings.

  First, the MCS selection table 132a according to the embodiment of the present invention will be described. The structure of the MCS selection table 132a is shown in FIG. The MCS selection table 132a includes items of index No (I), MCS modulation method and coding rate, CIR, error rate, and data amount. A unique number for identifying calibration data is set in the Intex No (I). As the MCS modulation scheme and coding rate, the MCS modulation scheme and coding rate of the calibration data transmitted from the base station 300 to the terminal 200 are set. For example, there are modulation schemes such as BPSK, QPSK, 16QAM, and 64QAM, and any of these schemes is set. The coding rate includes coding rates such as 1/2, 3/4, and the coding rate corresponding to the modulation scheme is set. The CIR for the calibration data transmitted from the terminal 200 that has received the calibration data to the base station 300 is set in the CIR. In the error rate, an error rate for the calibration data transmitted from the terminal 200 that has received the calibration data to the base station 300 is set. In the data amount, a data amount for the calibration data transmitted from the terminal 200 that has received the calibration data to the base station 300 is set.

  Next, the terminal information table 133a will be described. The configuration of the terminal information table 133a is shown in FIG. The terminal information table 133a includes items of terminal name, MCS modulation scheme and coding rate, CIR threshold, error rate threshold, and data amount threshold. As the terminal name, a unique name assigned to each terminal 200 is set. The MCS modulation scheme and coding rate selected when the base station 300 transmits transmission data are set as the MCS modulation scheme and coding rate. The modulation scheme and coding rate are the same as the modulation scheme and coding rate in the MCS selection table 132a. An allowable CIR range between the base station 300 and the terminal 200 is set as the CIR threshold. As the error rate threshold, an allowable range (such as an upper limit value) of an error rate between the base station 300 and the terminal 200 is set. In the data amount threshold, an allowable range of the data amount of calibration data for performing accurate communication quality measurement is set.

  When the CIR decoding unit 123a decodes the CIR information of the calibration data input from the demodulation unit 122, the CIR decoding unit 123a outputs the CIR information to the table rewriting unit 131a, the scheduler 143a, the MCS selection unit 144a, and the quality detection unit 151. When the error rate decoding unit 124 a decodes the error rate information of the calibration data input from the demodulation unit 122, the error rate decoding unit 124 a outputs the error rate information to the table rewriting unit 131 a and the quality detection unit 151. When the data amount decoding unit 125 decodes the data amount information of the calibration data input from the demodulation unit 122, the data amount decoding unit 125 outputs the data to the table rewriting unit 131 a and the quality detection unit 151. The quality detection unit 151 inputs the CIR from the CIR decoding unit 123a, the error rate from the error rate decoding unit 124a, and the data amount from the data amount decoding unit 125, and the CIR threshold and error of the corresponding terminal 200 from the terminal information table 133a. Enter the rate threshold and the data amount threshold, determine whether the CIR is within the range of the CIR threshold, the error rate is within the range of the error rate threshold, and the data amount is within the range of the data amount threshold. Detecting what is being done. Then, the quality detection unit 151 outputs the detection result of the quality measurement based on the calibration data to the measurement priority control unit 152. Based on the quality measurement detection result output from the quality detection unit 151, the measurement priority control unit 152 determines the priority of the terminal 200 that performs quality measurement using calibration data and the amount of calibration data corresponding to the terminal 200. The priority order for the terminal 200 and the amount of calibration data are output to the scheduler 143a.

  The table rewriting unit 131a receives the CIR of the calibration data (I) from the CIR decoding unit 123a, the error rate of the calibration data (I) from the error rate decoding unit 124a, and the calibration from the data amount decoding unit 125. When the data amount of data (I) is input and the MCS modulation method and coding rate of calibration data (I) are input from the MCS selection unit 144a, the input CIR, error rate, data amount, MCS modulation method and The coding rate is set in the MCS selection table 132a. For example, the table rewriting unit 131a inputs the CIR “c3” of the calibration data (3) from the CIR decoding unit 123a, and inputs the error rate “e3” of the calibration data (3) from the error rate decoding unit 124a. When the error rate “d3” of the calibration data (3) is input from the quantity decoding unit 125 and the modulation method “q3” and the coding rate “r3” of the calibration data (3) are input from the MCS selection unit 144a, FIG. As shown in FIG. 2, the modulation method of MCS corresponding to the index No (I) “3” is “q3”, the coding rate is “r3”, the CIR is “c3”, the error rate is “e3”, and the data amount is “D3” is set.

  If the transmission data is stored in the buffer 141, the scheduler 143a extracts the transmission data from the buffer 141, and extracts the CIR from the CIR decoding unit 123a corresponding to the destination terminal 200. Next, the scheduler 143a schedules transmission data based on this CIR, and outputs a transmission destination and transmission data to the MCS selection unit 144a. If the transmission data is not stored in the buffer 141, the scheduler 143a extracts the calibration data from the buffer 142, and further inputs the priority order and the data amount of the calibration data for the terminal 200 from the measurement priority control unit 152, Based on the priority and the data amount, a conversion rate (hereinafter referred to as a rate) of the transmission destination and the calibration data is determined, and the transmission destination, calibration data, and the rate of the calibration data are output to the MCS selection unit 144a. The calibration data rate includes a low rate, a medium rate, and a high rate, and corresponds to the MCS modulation method and coding rate. If the rate is low, the amount of calibration data is small, and if the rate is high, the amount of calibration data is large. For example, if the modulation method is “QPSK”, the coding rate is “1/2”, the modulation method is “BPSK”, and the coding rate is “1/2”, the rate is low, the modulation method is “QPSK”, the code If the coding rate is “3/4” or the modulation method is “16QAM” and the coding rate is “1/2”, the medium rate is obtained. The modulation method is “16QAM” and the coding rate is “3/4” or modulation. If the method is “64QAM” and the coding rate is “3/4”, the rate is high.

  When the MCS selection unit 144a transmits transmission data, the CIR is extracted from the CIR decoding unit 123a corresponding to the transmission destination terminal 200, and the error rate threshold corresponding to the transmission destination terminal 200 is extracted from the terminal information table 133a. Then, based on this CIR, the MCR modulation method and coding rate that fall within the error rate threshold range are selected from the MCS selection table 132a, and the selected MCR modulation method and coding rate are set in the MCR of the terminal information table 133a. Set to modulation method and coding rate. Then, the MCS selection unit 144a outputs the transmission destination, transmission data, and the MCR modulation scheme and coding rate to the modulation unit 145. For example, the transmission destination is “terminal B”, the CCS input from the CIR decoding unit 123 a corresponding to “terminal B” by the MCS selection unit 144 a is “cb”, and the terminal name “terminal B” of the terminal information table 133 a is corresponding. If the error rate threshold is “eb”, the MCS modulation scheme “q3” and the coding rate “r3” within the range of the error rate threshold “eb” based on the value of “cb” are obtained from the MCS selection table 132a. Selected. By this selection, “q3” is set as the MCS modulation scheme corresponding to the terminal name “terminal B” in the terminal information table 133a, and “r3” is set as the MCS coding rate. Further, when the MCS selection unit 144a transmits calibration data, based on the transmission destination output from the scheduler 143a and the rate of calibration data, the MCS selection table 132a selects the MCS modulation method and coding rate, The transmission destination, the calibration data, and the MCR modulation method and coding rate are output to the modulation unit 145.

  FIG. 4 is a flowchart of the MCS selection procedure for transmission data and calibration data according to the embodiment of the present invention. Hereinafter, the steps will be described in the order of the flowchart of the MCS selection procedure.

(Step S10)
First, the scheduler 143a determines whether there is transmission data in the buffer 141. When there is transmission data (Yes in step S10), the transmission data stored in the buffer 141 is output to the MCS selection unit 144a, and the process proceeds to step S20 to select the MCS modulation method and coding rate of the transmission data. When there is no transmission data (No in step S10), the process proceeds to step S40 for determining the priority of the transmission destination before transmitting calibration data.

(Step S20)
When Step S10 is Yes, the MCS selection unit 144a extracts the CIR from the CIR decoding unit 123a corresponding to the transmission destination terminal 200, and extracts the error rate threshold corresponding to the transmission destination terminal 200 from the terminal information table 133a. Then, based on this CIR, the MCR modulation method and coding rate that fall within the error rate threshold range are selected from the MCS selection table 132a, and the selected MCR modulation method and coding rate are set in the MCR of the terminal information table 133a. Set to modulation method and coding rate. Then, the MCS selection unit 144a outputs the transmission destination, the transmission data, the MCR modulation scheme and the coding rate to the modulation unit 145.

(Step S30)
Modulation section 145 receives the destination, transmission data, and MCR modulation scheme and coding rate from MCS selection section 144a, modulates the transmission data with the modulation scheme and coding rate, and outputs the result to transmission RF section 146. The transmission RF unit 146 converts transmission data from a digital signal to an analog signal, performs up-conversion, and outputs the converted data to the antenna duplexer 110.

(Step S40)
When Step S10 is No, the measurement priority control unit 152 corresponds to the priority order of the terminal 200 that performs quality measurement based on the calibration data based on the detection result of the quality measurement output from the quality detection unit 151, and the terminal 200. The amount of calibration data is determined, and the priority order for the terminal 200 and the amount of calibration data are output to the scheduler 143a. A terminal having a lower transmission rate determined by the selected MCS sets a higher priority. That is, among the MCSs stored in the terminal information table 133a, the MCS having the slower transmission rate has a longer time (number of slots) for transmitting calibration data using the MCS.

(Step S50)
The scheduler 143a extracts the calibration data from the buffer 142, and further inputs the priority order and the data amount of the calibration data for the terminal 200 from the measurement priority control unit 152, and based on the priority order and the data amount, the destination and the calibration are input. The data rate is determined, and the transmission destination, calibration data, and calibration data rate are output to the MCS selection unit 144a.

(Step S60)
The MCS selection unit 144a selects an MCS modulation scheme and a coding rate from the MCS selection table 132a based on the transmission destination and calibration data rate output from the scheduler 143a, and transmits the transmission destination, calibration data, and MCR. The modulation scheme and coding rate are output to modulation section 145.

(Step S70)
The modulation unit 145 receives the transmission destination, calibration data, and MCR modulation method and coding rate from the MCS selection unit 144a, modulates the calibration data with the modulation method and coding rate, and outputs the modulation data to the transmission RF unit 146. . The transmission RF unit 146 converts the calibration data from a digital signal to an analog signal, performs up-conversion, and outputs it to the antenna duplexer 110.

(Step S80)
When the calibration data is transmitted to the terminal 200, the CIR, error rate, and data amount with respect to the calibration data are transmitted from the terminal 200 to the base station 300. Therefore, the reception RF unit 121 of the base station 300 performs the calibration from the antenna sharing device 110. CIR, error rate, and data amount of the operation data are received.

(Step S90)
The quality detection unit 151 inputs the CIR from the CIR decoding unit 123a to the corresponding terminal 200, the error rate from the error rate decoding unit 124a, the data amount from the data amount decoding unit 125, and the corresponding terminal 200 from the terminal information table 133a. The CIR threshold, the error rate threshold, and the data amount threshold are input, and it is determined whether the CIR is within the CIR threshold range, the error rate is within the error rate threshold range, and the data amount is within the data amount threshold range. If it is within (Yes in step S90), since the quality measurement has been properly performed, the process proceeds to step S100 in which the MCS selection table 132a is updated. Further, when it is not within the threshold range (No in step S90), since the quality measurement is not properly performed, the quality detection unit 151 proceeds to step S110 in which the measurement priority control unit 152 outputs the quality measurement detection result. .

(Step S100)
When Step S90 is Yes, the table rewriting unit 131a inputs the CIR from the CIR decoding unit 123a, the error rate from the error rate decoding unit 124a, the data amount from the data amount decoding unit 125, and the corresponding calibration from the MCS selection unit 144a. When the MCS modulation method and coding rate of data are input, the CIR, error rate, data amount, MCS modulation method and coding rate are set in the MCS selection table 132a of the corresponding terminal 200, and the process returns to step S10.

(Step S110)
When step S90 is No, the quality detection unit 151 outputs the quality measurement detection result to the measurement priority control unit 152 and returns to step S10.

  As described above, according to the embodiment of the present invention, it is possible to accurately measure the communication quality between the base station and the terminal by transmitting calibration data with an appropriate MCS modulation scheme and coding rate. it can. In addition, since calibration data is transmitted at an appropriate frequency, it is possible to prevent a decrease in throughput of transmission data.

  As mentioned above, although this invention was demonstrated by specific embodiment, it cannot be overemphasized that the said embodiment is an illustration of this invention and is not limited to this embodiment.

The characteristics of the above embodiment are summarized as follows.
(1) The wireless communication system of the present invention transmits calibration data from a base station to a plurality of terminals communicating with the base station, and based on an error rate of the calibration data, between the base station and the terminal In a wireless communication system that detects communication quality and selects a communication mode of transmission data to be transmitted to the terminal based on the detected communication quality, the base station stores a communication mode used by each of the plurality of terminals Storage means; and priority setting means for transmitting the calibration data using a communication mode with a low transmission rate preferentially among the communication modes stored in the storage means.
(2) The wireless communication system of (1) is characterized in that when there is the transmission data, the transmission data is preferentially transmitted, and when there is no transmission data, the calibration data is transmitted.
(3) The storage unit of the wireless communication system according to (1) or (2) further stores the CIR, the error rate, and the data amount of the calibration data.
(4) The communication mode of the wireless communication system according to any one of (1) to (3) is configured by either a modulation method and a coding rate, or a modulation method or a coding rate. .
(5) In the communication mode selection method of the wireless communication system of the present invention, the calibration data is transmitted from the base station to a plurality of terminals communicating with the base station, and the base station and the base station are based on the error rate of the calibration data. In a wireless communication system that detects communication quality between the terminals and selects a communication mode of transmission data to be transmitted to the terminals based on the detected communication quality, the base station is used by each of the plurality of terminals A storage step of storing a communication mode; and a priority setting step of transmitting the calibration data by using a communication mode having a low transmission rate out of the communication modes stored in the storage step. It is characterized by.
(6) The wireless communication system of the invention transmits calibration data from a base station to a plurality of terminals that communicate with the base station, and performs communication between the base station and the terminal based on an error rate of the calibration data. In a wireless communication system that detects quality and selects a communication mode of transmission data to be transmitted to the terminal based on the detected communication quality, receiving means for receiving the CIR, error rate, and data amount of the calibration data from the terminal A quality measuring means for detecting communication quality between the base station and the terminal from the CIR, the error rate and the data amount, and a transmission destination of the calibration data based on a detection result of the quality detecting means, A measurement priority control means for determining a rate of the calibration data, and the transmission determined by the measurement priority control means. A transmission unit that transmits the calibration data to the terminal serving as a receiver; a communication mode that selects the communication mode of the transmission data based on the communication mode of the calibration data, the CIR, and the error rate; And selecting means.
(7) The wireless communication system according to (6) is characterized in that when there is the transmission data, the transmission data is preferentially transmitted, and when there is no transmission data, the calibration data is transmitted.
(8) The wireless communication system according to (6) or (7) is characterized by comprising storage means for storing the communication mode, the CIR, the error rate, and the data amount of the calibration data.
(9) The communication mode of the wireless communication system according to any one of (6) to (8) is characterized by being configured with either a modulation method and a coding rate, or a modulation method or a coding rate. .
(10) In the communication mode selection method of the wireless communication system of the present invention, the calibration data is transmitted from the base station to a plurality of terminals communicating with the base station, and the base station and the base station are based on the error rate of the calibration data. In a communication mode selection method of a wireless communication system that detects communication quality between the terminals and selects a communication mode of transmission data to be transmitted to the terminals based on the detected communication quality, the CIR of the calibration data from the terminal A reception step of receiving an error rate and a data amount, a quality measurement step of detecting communication quality between the base station and the terminal from the CIR, the error rate and the data amount, and a detection result of the quality detection step Measurement priority control for determining the calibration data transmission destination and the calibration data rate based on And, based on the transmission step of transmitting the calibration data to the terminal as the transmission destination determined by the measurement priority control step, the communication mode of the calibration data, the CIR, and the error rate And a communication mode selection step of selecting the communication mode of the transmission data.

  The present invention is suitable for a wireless communication system, but is not limited to a wireless communication system, and can be applied to general apparatuses for measuring communication quality.

DESCRIPTION OF SYMBOLS 10 ... Wireless communication system 20 ... Wireless communication system 100 ... Base station 110 ... Antenna duplexer 111 ... Antenna 120 ... Receiving unit 120a... Receiving unit 121... Receiving RF unit 122... Demodulating unit 123... CIR decoding unit 123a. Rate decoding unit 124a... Error rate decoding unit 125... Data amount decoding unit 130... Table updating unit 130a... Table updating unit 131. ... Table rewriting unit 132 ... MCS selection table 132a ... MCS selection table 133 ... Terminal information table 133a ... Terminal information table 140 ... Transmission unit 140a ... Send Part 141 ..... buffer (transmission data)
142 ... Buffer (for calibration data)
143... Scheduler 143 a... Scheduler 144... MCS selection unit 144 a... MCS selection unit 145. ... Terminal information monitoring unit 151 ... Quality detection unit 152 ... Measurement priority control unit 200 ... Terminal 300 ... Base station

Claims (1)

Calibration data is transmitted from the base station to a plurality of terminals that communicate with the base station, and the communication quality between the base station and the terminal is detected based on the error rate of the calibration data. In a wireless communication system that selects a communication mode of transmission data to be transmitted to the terminal based on:
The base station has storage means for storing a communication mode used in each of the plurality of terminals;
Priority setting means for transmitting the calibration data by using a communication mode having a low transmission rate among communication modes stored in the storage means,
A wireless communication system comprising:

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